The NAVDAT project is compiling existing age, chemical, and isotopic data from Late Cretaceous to Holocene extrusive and intrusive igneous rocks from the western United States, British Columbia, and northern Mexico into a web-accessible electronic database. NAVDAT will be integrated into a geographic information system (GIS) to allow visualization of complex age-compositional patterns in volcanism throughout the study region. The addition of necessary relational and graphical tools will allow users of the database to address a wide variety of issues concerning the geologic evolution and present volcanic state of western North America.